Carbon dioxide gas is recognized among principal absorbers of radiation in the Earth's atmosphere. Moreover, carbon dioxide molecules are ubiquitous in the Universe. Being a dominant gas phase constituent in the atmospheres of Mars and Venus, carbon dioxide is responsible for a variety of physico-chemical processes in atmospheres of these terrestrial group planets. Weak intermolecular interaction among carbon dioxide molecules results in formation of van der Waals complexes or dimers. Estimates show that (CO$- 2$/)$-2$/ dimers are the most abundant constituent in the surface layers of Venusian atmosphere after CO$-2$/ itself. Although carbon dioxide in the gas phase is not appreciably abundant in the interstellar media, recent spectroscopic observations provide strong indications of widespread CO$- 2$/-ices and CO$-2$/-rich ice mantles in molecular clouds. All these justify carrying out extensive experimental and theoretical studies of the carbon dioxide molecules in pairwise and higher order interactions. Crucial role in these investigations belongs to laboratory spectroscopic studies which imply a variety of methods, tools and external parameters. Present paper aims at reviewing infrared and Raman spectroscopy of CO$-2$/ dimers formed in adiabatically cooled flows, in a pressurized static gas sample, and while trapped in low-temperature matrices.
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